The 54-year-old who has spent more than a decade in prison for the murder of Teresa Halbach, told the Daily Mail his relationship with Hartman began with letters and phone calls, but the pair met in person last week when Hartman visited him at the Waupun Correctional Institute in Wisconsin.

According to her social media profiles, Hartman is a self-described bankruptcy specialist, legal assistant and "supporter of the wrongfully convicted Steven Avery."

Avery was launched into the spotlight when a Netflix docu-series chronicled his release from prison after spending 18 years behind bars for a rape he didn’t commit and his eventual arrest on murder charges soon after his release.

Avery was convicted in 2007 of killing Halbach, a 25-year-old photographer for "Auto Trader" magazine who vanished while taking photographs of a van at the Avery family's salvage yard in Manitowoc County, Wisconsin.

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Avery’s attorney is seeking permission to perform extensive scientific tests on evidence she believes will show he’s innocent.

It’s not Avery’s first engagement and, if the two wed, it won’t be his first marriage. Avery had previously wed Lori Mathiesen and was also formerly engaged to Sandy Greenman, a woman featured at the end of the Netflix series, and Jodi Stachowski, who also appeared in episodes.

"He threatened to kill me, and my family and a friend of mine," Stachowski said in an interview with HLN’s "Nancy Grace" show just as the Netflix documentary about Avery’s conviction was sweeping the nation.

In her first interview following the series' release, Stachowski said she endured an allegedly violent, volatile and abusive two-year relationship with Avery.

While neither Avery nor his lawyer have not commented on the abuse allegations, Stachowski said she asked Avery multiple times if he killed Halbach, and each time he adamantly denied it. She also said she had not seen Avery physically hurt others during their relationship.